Synthesis of 5,10-Secosteroids and their evaluation as selective inhibitors of steroid-transforming enzymes. These compounds are designed as inhibitors of delta 5-3-ketosteroid isomerase, of 3- and (3 and 17) beta-hydroxysteroid dehydrogenases, and of processes involved in the oxidative degradation of lanosterol and of cholesterol. The mechanisms by which enzyme inhibition occurs will be studied.